Hydraulic operator



March 21, 1933. w. J. wooos HYDRAULIC OPERATOR Filed Aug. 15,

Ihvenbori William J. WOOGIS,

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Patented Mar, 21, 1933 UNITED STATES PATENT OFFICE WILLIAM J. WOODS, OFSCmC'I'ADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC A CORPORATION OF NEWYORK mmumo owns-ma Application filed. August 15, 1930. Serial No.475,424.

My invention relates to improvements in electro-hydraulic operatingmeans of the type described in a copending application of Walter 0. Lum,Serial No. 415,341, filed December 19, 1929 and assigned to the sameassignee as the present application.

In devices of the above type a piston operated by a motor drivenlmpeller carried thereby moves within a cylinder or casing containing afluid, such for example as oil. The piston is connected to operate awork engaging member and the load on the work engaging member may' varybetween wide limits. When the hydraulic o crating means hereinafterreferred to as the operator is heavily loaded, the piston returns to itsinitial position rapidly upon deenergization of the driving motorthereof, and undesirable stresses and strains may result, since underthese conditions the normal dashpot effect is insuflicient to cushionthe return movement of the piston under the heavy load. Again in someapplications of the hydraulic operator it is desirable to obtain anaccentuated dashpot or time delay effect not possible in a standardoperator. v Hence, it is the principal object of my invention to cushionthe final movement of an electro-hydraulicoperator of the above type toits imtial position without however unduly retarding the entire returnmovement thereof. q

It is another object of my invention to produce an accentuated dashpotor time delay efiect on the return stroke of the operator.

In the preferred embodiment of my in-' vention I provide a fluid casingor cylinder in which is slidably mounted a plunger or piston whichiscaused to move to its upper limit by means of an im eller carried by'the piston proper, the impe ler being .energized by a motor mounted onthe casing proper. The piston is attached to a work-engaging mem: .berextending without the casing and connected to operate some form ofapparatus. The. piston is provided with passageways therethrough so thatthe oil can .pass through the piston as it moves up or down in responseto rotation of the impeller or to the load exerted upon thework-engaging member upon deenergization of the impeller. At the bottomof the casing and resiliently supported is, a bafiie member whichengages the piston in its downward movement a short distance from theend of its stroke. This bafile cooperates with the iston to close thepassageways extending t erethrough and thereby prevents a free flow ofoil through the piston proper. The eifect of this operation is tocushion the return of the piston to its lower or initial position. h amodification the piston is provided with studs on which thebaflle isslidably supported at a depth below the piston to give a proper lengthof stroke. In the drawing, Fig. 1 represents a cross section of myhydraulic operator with the work-engaging member and piston in the upperposition. Fig. 2 represents a cross sec: tion of the piston showing thedetails of the passageways therethrough. Fig. 3 represents a partialcross section of a modification of my hydraulic operator.

In Fig. 1 the casing 10 is filled with oil and'lower position therein.An impeller 13 is rotatably supported in the piston. The

casing 10 is provided with a coverin or cylinder head 11 which supportsthe electric motor 12 for driving the impeller13 by means of the splinedshaft 33. Bearings 34 and 234 are provided for the splinedshaft. A cover12 having a bea'ring12 therein "is provided for the motor 12. v a

The piston consists of two parts 14 and 21, the upper portion21 havingextensions 22 and 23 thereon for supporting the push rods 24 and 25which are: connected to the bridging member 31 supporting. the workengaging eye 32. Surrounding the push rods and supported .by theextensions 22 and 23 are the stop members 29 and 30 for limiting theupward movement of the piston 14. These push rods slide in the bearings26 and 26' carried by the cylinder head 11. The bearings are providedwith the grooves or slots 27 and 28 which permit the return of any oilwhich may have adhered to the push rods and passed by the bearings whichact as wipers in the upward movement of the push rods 24 and 25.Clearances are provided in the cylinder head 11 for permitting the pushrods to extend therethrough without contact therewith which permits oilcarried up by the push rods to return to the casing.

In Fig. 2 is shown a cross section of a piston comprising the two parts14 and 21. Passageways such as 15 and 16 in the top part of the pistonpermit oil to contact with the upper part of the impeller 13. Otherpassageways such as 18 lead oil from above the piston to the cup-shapedportion 17 beneath the impeller. Thus oil is led to the impeller fromboth the top and the bottom sides thereof. Other passageways such as 19and 20 ofi'er a passage in a radial direction from the impeller bladesto the under side of the piston. Thus when the impeller is rotated bymeans of the motor 12 oil is drawn into the top and under sides of theimpeller and expelled in a radial direction to the passageways 19 and20.

The bearings 26 and 26' act as wipers for the push rods. However, oilwhich adheres to the push rods 24 and 25 will return to the space abovethe bearings because of the clearance in the cylinder head around thepush rods. The oil which is there received will then return to thecasing by means of the slots 27 and 28 in the bearings.

Mounted in the lower part of the casing 10 is the baflle member 35resiliently supported by means of springs 36. The whole operator ispivotally supported by means of the eye 37.

The operation of the device is as follows: When it is desired to raisethe work engaging' member 32, the motor 12 is energized to rotate theshaft 33 which in turn drives the impeller 13. The oil is received bythe impeller through the passageways 15 and 16 to the upper side of theimpeller and the passageways such as 18 and 17 to the under side of theimpeller and discharged therefrom in a radial direction through thepassageways 19 and 20. This causes a pressure differential which exertsafo rce on the bottom of the cylinder to cause it to be raised withinthe cylinder, the rate at which the piston is raised depending upon thearea of the piston, the load exerted thereby, the impeller diameter andthe rate of rotation of the motor. When the piston reaches peller spinsin the oil without effecting further operation of the device.

'When the motor 12 is deenergized the load thereon causes the pistion tosettle, the oil then returning from the under side of the piston throughthe passageways to the top I side of the piston. Since the flow of oilis restricted by the passageways a dashpot or time delay effect isobtained. When heavily loaded however the piston settles quickl untilit'engages the baflie 35. This b e member which isof circular shapeengages the under side of. the piston 14 and closes the ports to thepassageways 19 and 20, thereits upper position the imby limiting andrestricting the flow of oil back through the piston. The springs and theoil together thus cause a cushioning effect of the return of the pistonto its lower position and prevent impact between the piston and thecasing which prevents undesirable stresses and strains in the operator.

In the view shown in Fig. 3, the baflle member 35' is supported upon thepiston 14 by means of studs such as 40 and 40. The baflle is providedwith the orifices such as 43 and 44 for a purpose to be described later.The operator in its upper position supports the baflle as shown. Whenthe operator motor is deenergized the piston descends rapidly. Since thebafile is slidably mounted upon the studs 40 and 41 the baffle will beable to move with respect to the piston. When the support offered by thestuds is removed upon the descent of the piston to its lower positionthe baflie will tend to settle but its settling in the oil is very slowin comparison to the movement of the piston and the piston will overtakethe baflle in its movement to the bottom of the casing. When this takesplace the oil ports in the piston proper are closed by the baflle andonly a restricted flow is permitted therethrough by means of theorifices such as 43 and 44 in the baflie proper. These orifices can beeither increased or decreased in number or in size to obtain the desiredrate of movement of the piston during the last portion of the returnstroke. Such a control to obtain an accentuated dashpot efl'ect whichresults in a slow return is desirable for example in fire pump controlswhere a quick operation to one position with a slow return is desired.The boss 42 at the bottom of the casing and boss 41 on the bottom of thepiston engage each other when the piston is in its lower position toprevent contact of the studs with the bottom of the casing proper. Ofcourse, when the piston reaches its lower position and the pressurebeneath the piston becomes equalized the bafile 35' slowly settles tothe bottom of the casing and when the motor is again energized to movethe piston the studs carry the baflle with it to theposition shown inFig. 3.

It will thus be seen that I have provided a novel and efficient meansfor preventing impact in an electro-hydraulic operator of the above typewhich is certain in action and will prevent shock and strain to thehydraulic operator parts.

The embodiment of the invention illustrated and described herein hasbeen selectedfor the purpose of clearly setting forth the principlesinvolved. It will be apparent, however, that the invention issusceptible of being modified to meet the different conditionsencountered in its use, and I, therefore, aim to cover by the appendedclaims all of the modifications within the true spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electro-hydraulic operator including a fluid-containingcylinder,-a piston operable within said cylinder between two positionsand biased to one of said positions, said piston being provided withpassageways therethrough, an electrically driven pump havingcommunication with said passageways for controlling the transfer offluid between opposite sides of the piston through said passageways inone direction to move the piston from its biased position to the otherposition when said pump is energized, and a movable bafile meanscooperating with said piston and effective to control the flow of fluidthrough the passageways of said piston in the reverse direction forproducing a time-delay effect on said piston when said pump isdeenergized and said piston moves to the biased position.

2. An electroydraulic operator having a cylinder With a fluid therein, apiston movable in the fluid in said cylinder between two positions andbiased to one of said positions, said piston having a fluid passagetherethrough, a pump communicating with said passage, an electric motorfor operating said pump to transfer fluid through said pas sage in onedirection from one side of said piston to the other side of said pistonto move said piston from said biased position to the other position whensaid motor is energized, and a baflle means cooperating with said pistonto control the flow of fluid through said passage in the reversedirection from said other side of the piston to said one side of thepiston upon deenergization of said motor whereby a time-delay. effectupon the move ment of said piston to its biased position is obtained.

3. A hydraulic operator including a fluid cylinder, a piston movablebetween two p0 sitions within said cylinder, communicating passagesextending through said piston for permitting fluid to pass therethrough,a pump associated with the piston for movement therewith and forcommunication with said passageways for controlling the transfer offluid between opposite sides of the piston to control the movement ofthe piston to one of said positions, said passageways when said pistonis moved to the other of said positions producing a dashpot effect toretard movement of said piston to said other position and baflle meansresiliently mounted adjacent said other position for closing saidpassages in said piston for increasing the dashpot effect of saidmemberon movement to said other position.

4. An electro-hydraulic operator havin a cylinder with fluid therein, apiston mova le in the fluid in saidcylinder between two positionsandbiased to one of said positions, said piston having a fluid. passagetherethrough,

a pump assoclated with the piston for movement therewith and havingcommunication with said passage, an electric motorfor operating saidpump to transfer the fluid through v the other position when said motoris ener- I gized, and baflie means movably'mounted in the cylinder tocooperate with thepump for controlling the transfer of fluid throughsaid passage in the reverse direction to provide a time delay effectupon movement of the piston from said other position to its biasedposition when said motor is deenergized.

' 5.- An electro-hydraulic operator havin a cylinder with fluid therein,a piston mova le in the fluid in said cylinder between two positions andbiased to one of said positions, a pump associated with the piston formovement therewith and provided with inlet and outlet passages onopposite sides of the piston, an electric motor for operating said pumpto transfer the fluid through said passages in one direction between theopposite sides of the piston to control movement of the piston from itsbiased position to the other position when said motor is energized,

and baflie means cooperating with the pump for controlling the transferof fluid between I the opposite sides of the piston through saidpassages in the reverse direction to provide a dashpot efiect uponmovement of the piston from the other position to its biased positionwhen said motor is deenergizedr 6. A hydraulic operator including acasing, a fluid therein, a piston within said casing movable between anupper position and a lower position, said piston being biased to itslower position, passageways in said pis ton tor permitting said fluid topass through said piston upon pump associated with said piston andmovable therewith' and having communication movement of said piston, a

with said passageways for transferring the fluid therethrough to movethe piston to its upper position, a baflie resiliently mounted near saidlower position of said piston for cooperatin with said piston toclosethe passageways erein when said piston moves to its lower position,said baflle thus preventing impact of said piston and said casing.

7. An electroydraulic operator includin a casing, a fluid therein, apiston within said casing movable between an upper position and a lowerposition, said-piston being biased to its lower position, passageways insaid piston for permitting fluid to pass through said piston uponmovement of said piston, a pump associated with said piston and movabletherewith and having communication with said passageways,-an electricmotor for driving said pump for transferring the fluid between oppositesides of said piston to move said piston to its upper position when saidmotor is energized, a baflie slidably supported by said piston andcooperating with said piston to c ose the passageways therein when saidpiston moves from its upper position to its lower position upondeenergization of said motor, said bafile acting to produce a time-delayaction in the movement of said piston to its lower position.

8. An electro-h draulic operator including a casing, a flu1d therein, apiston within said casing movable between an upper position and a lowerposition, said piston being biased to its lower position, passageways insaid piston for permitting said fluid to pass through said piston uponmovement of said piston, a pump associated with said piston and movabletherewith and having communication with said passageways, and an 7electric motor for driving said pump for transferring the fluidtherethrough to move the piston to its upper osition when said motor isenergized, a ba e slidably supported by said piston and cooperating withsaid piston to close the passageways therein when said piston moves toits lower position upon deenergization of said motor, said baflie beingprovided with orifices therein for determimng the restricted flowthrough said piston whereby a time-delay action of the movement of saidpiston to its lower position is obtained thereby preventing impact ofsaid piston and said casing.

9. An electro-hydraulic operator having a cylinder with fluid therein, apiston movabl in the fluid in said cylinder, a pump associated with thepiston for movement therewith and provided with inlet and outletpassages on opposite sides of the piston, an electric motor for saidpump for transferring fluid therebetween opposite sides of said pistonto move the piston in one direction upon operation of the pump when saidmotor is energized, means for biasing the piston for movement in theother direction when operation of the pump is stopped upondeenergization of said motor and baflie means cooperating with theoutlet passages of the pump for providing a dashpot effect in themovement of the piston in said other direction.

In witness whereof, I have hereunto set my hand this 14th day of August,1930.

WILLIAM J. WOODS.

